This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/SE98/00844 which has an International filing date of May 8, 1998 which designated the United States of America.
The present invention relates to a spring mattress comprising a plurality of interconnected coil-spring elements. The mattress having at least two layers extending in parallel with the plane of the mattress and each exhibiting a different properties of resilience.
Quality spring mattresses today normally comprise two superposed layers of coil springs disposed between the bed frame and the surface of the mattress. In some cases the springs in one of the spring layers are enclosed in an external cover, usually made from a textile material. As a result of the provision of these outer covers the springs assume a partly biased position in the normal, unloaded condition of the mattress.
However, these mattresses are comparatively complicated to manufacture, since they comprise a large number of different components. They are also relatively cumbersome to assemble, considering that each spring in the biased layer must be sewn into a separate cover, in addition to which the springs thereafter must be tied to one another in order to form a layer. The layer then must be anchored to a lower, non-biased layer and to frame parts and the like.
Consequently it is an object of the subject invention to provide a spring mattress and a method of manufacturing the same, the mattress being of a kind that comprises layers exhibiting different qualities of resilience but that contains fewer components, while at the same time the mattress is more convenient and less expensive to manufacture than hitherto known mattresses of this kind.
According to a further aspect of the invention a mattress of the kind referred to is provided, which improves the user""s comfort because the layer having the lesser bias is turned towards the surface of the mattress and/or because the springs occupying this layer are individually resilient.